Mercury bellows pump



25, 1956 E. s. ROBINSON ETAL MERCURY BELLOWS PUMP Filed Aug. 19, 1955WITNESSES N VEN TO I Eu ene 5. Robinson Ar bar 6. Briesmeisler Berl/wsB. M lmeer United States Patent 0 MERCURY BELLOWS PUMP Eugene S.Robinson, Arthur C. Briesmeister, and Berthus B. Mclnteer, Los Alamos,N. Mex., assignors to the United States of America as represented by theUnited States Atomic Energy Commission Application August 19, 1955,Serial No. 529,592

3 Claims. (Cl. 230-85) undesirably large volumes of either liquids oractuating gases which are allowed to come in contact with the gas beingpumped. When a radioactive gas is being pumped, the danger ofcontamination increases with the volume of material in contact with theradioactive gas. Furthermore, many of the pumps of the prior art use oilto create a pressure or vacuum seal. With the handling of certain gases,the use of oil is undesirable because of the reaction between the liquidand the pumped gas. For example, tritium, a radioactive isotope ofhydrogen, is readily absorbed by oil, and a large proportion of thetritium will be lost in an oil system. Also, in the liquid piston pumpsof the prior art, thevalves are usually operated by floats which aresluggish and not positive in their action. The liquid piston in thepumps of the prior art does not completely expel the gas from thepumping chamber on each cycle and, consequently, the gas transfer is notfully positive and efiicient. Many of the pumps of the prior arttransfer a large quantity of gas per cycle, but the time between cyclesis very long. Since disturbances within most chemical process systemsshould be held to a minimum, it is more desirable to transfer or pump asmaller quantityof gas per cycle with,however,

a short time period between cycles.

The present invention provides a gas transfer pump which has positivevalve action, positive flow control, does not allow the gas being pumpedto come in contact with any other gas, and keeps the amount of fluid inthe pump to a practical minimum.

Therefore, it is an object of the present invention to provide a liquidpiston gas transfer pump wherein the actuating liquid is sealed from theatmosphere.

Another object of the present invention is to provide a liquid pistongas transfer pump wherein the valve action is positive.

Another object of the present invention is to provide a liquid pistongas transfer pump which has a high pumping rate and wherein all of thegas drawn into the transfer chamber is expelled at'the end of eachstroke.

Another object of the present invention is to provide a liquid pistongas transfer pump which has a high pumping rate and which will providean excellent ultimate vacuum on the inlet side.

Another object of the present invention is to provide a liquid pistongas transfer pump which is capable of pumping gases at a high pumpingrate with modest power requirements.

Further objects and advantages will become more apparent from thefollowing description and drawings, hereby made a part of thespecification wherein: Figure 1 is a cross-sectional view of a preferredembodiment of 2,775,399 Patented Dec. 25, 1956 the present invention,and Figure 2 is a detailed view of the outlet valve of Figure l. a

The embodiment of Figure 1 comprises a base 1, having bearing supports 2and a crankshaft 3 which is connected by coupling 4 to any suitablesource of rotational power.

Suspended from plate 6 above crankshaft 3 by means of supports 5 is abellows or similar compressible chamber 7 which is sealed to plate 6 onthe upper end. The lower portion of the bellows 7 is sealed to a plug 8by means of an O ring 9 or other similar sealing means. The plug 8contains a pivot pin 10 on which a connecting rod 11 is rotatablymounted. The lower end of the connecting rod 10 is rotatably mounted onthe eccentric portion of the crankshaft 3. In this manner, rotation ofthe crankshaft 3 will alternately compress and expand the bellows 7,resulting in movement of the plug 8 relative to plate 6. Vertical guides(not shown) are provided to insure controlled movement of the bellows 7.

Rigidly attached to plate 6 and sealed to the upper portion of thebellows 7 is a valve head 12 which contains a chamber 13 of knownvolume, an inlet 14 and outlet 15. The inlet 14 is closed or opened bymeans of a valve 16 which is resiliently connected to the plug 8. Inthis manner the upward movement of plug 8 will cause valve 16 to closethe gas inlet 14. A rod 17 is attached to the plug 8 opposite the outlet15, and a spring-actuated valve 18 is provided for sealing the outlet15. Thus, the upward movement of plug 8 and rod 17 will force valve 18to open, thereby connecting the chamber 13 to any associated system (notshown) connected to aperture '19.

A quantity of mercury or other suitable liquid is placed in the bellows7 and around the plug 8, so that when the bellows is in its mostexpanded position the mercury level is at a predetermined level A. Theratio of the volume 13 to that of the bellows 7 (minus the volume a ofplug 8) is such that upon full compression of the bellows 7, the levelof the mercury is raised to above the level of the valve 18. Thepresence of plug 8 keeps the mercury volume near a minimum.

The operation of the present invention is as follows;

1 The inlet 14 of valve head 12 is connected to any suitable source ofgas, and the outlet aperture 19 is connected to the system into whichthe gas is to be transferred. The coupling 4 is connected to anysuitable source of rotational power, and crankshaft 3 is therebyrotated. The rotation of crankshaft 3 moves connecting rod 11 up anddown so that through its pivot pin 10 the plug 8 is moved up and down.The plug 8 being attached to the bellows 7 is moved with relationthereto as the bellows is alternately compressed and expanded. On theupward movement of the plug 8 rod 17 moves up to open valve 18 at thetop of its stroke and the mercury in the bellows and between the top ofplug 8 and level A is forced upwardly through the known volume chamber13, past valve member 18, and into outlet 15, forcing ahead of it thegas in chamber 13. This same upward movement forces valve 16 to seat ininlet 14, thereby closing the inlet. It should be noted that valves 16and 18 are not open at the same time because of the resilient connectionbetween valve 16 and plug 8. Therefore the chamber from which the gas isbeing removed and the chamber into which the gas is being delivered arenot connected at any time. This feature is necessary to insure positive,efiicient pump action. The gas contained within the chamber 13 is forcedthrough the open valve 18 and through the seal formed by mercury inoutlet 15 left from the previous stroke, as hereinafter described, andon to the associated receiving system.

Figure 2. shows a detailed view of valve 18. Holes 20 in guide member 21allow the pumped gas to enter aperture 19 above the valve. Spring 22serves to keep valve 18 closed except when held open by rod .17 ofFigure 1, or except when the gas fills the chamber 13 at such a pressureas to force this valve open during the compression stroke.

After the plug 8 reaches its highest position, continued rotation ofcrankshaft 3 will move plug 8 downwardly, expanding the bellows andpermitting the mercury to return to volume 13. However, as the mercurylevel drops, valve 18 closes before all the mercury has left outlet 15.This action results in a complete vacuum (equal to the vapor pressure ofmercury) in chamber 13. As the mercury in plug 8 continues the downwardmovement, valve 16 is unseated and the source of gas thereby transferredis connected to the evacuated chamber 13. Gas enters through inlet 14and the cycle is then repeated.

Thus, it is apparent that the present invention provides a new and novelmeans for transferring quantities of gas 'from one system to another atreasonably high rates of speed. The pump contains no oil which maycontaminate the gas, and the liquid piston material which is allowed tocome in contact with corrosive or radioactive gases is confined withinaclosed chamber so that a hazard to operating personnel does not exist.The vacuum created on each pumping stroke is so excellent that thesource from which the gas is being transferred can be evacuated to adegree heretofore not possible. Furthermore, the valve action ispositive and the reliability of the pump is not dependent upon floatvalves which may stick or otherwise become inoperative.

While a certain specific embodiment has been shown and described, it isunderstood that various modifications may be made without departing fromthe scope of the invention as defined in the appended claims. Forexample, the bellows which seals the mercury from the atmosphere andallows the upward motion of plug 8 could be replaced by a metal pistonin a cylinder sealed by a suitable packing such as an O ring. Also thesource of power which imparts reciprocal motion to bellows 7 and plug 8may be any means for achieving that end. The liquid piston material,though described as mercury, could be any other liquid suitable for theconditions required.

What is claimed is:

1. A gas transfer pump comprising in combination a bellows, a plugattached to and sealing one end of said bellows, a valve head sealed tothe other end of said bellows, said valve head containing a gas inletand gas outlet and a transfer chamber, said outlet being located higherthan said inlet, said transfer chamber communicating with said other endof said bellows, valve means for controlling the flow of gas throughsaid outlet and inlet, means attached to said plug for actuating saidvalve means, a quantity of liquid in said bellows, means for moving saidbellows and plug with respect to said valve head whereby the liquidwithin said bellows is forced into said gas transfer chamber and saidvalve means is actuated to control the flow of gas through said chamber.

2. A gas transfer pump comprising a bellows, a plug sealed to one end ofsaid bellows, a valve head sealed to the other end of said bellows, saidvalve head containing a gas inlet and gas outlet and a known volumechamber communicating with said other end of said bellows, said outletbeing located higher than said inlet, valve means for controlling thefiow of gas through said outlet and inlet, means attached to said plugfor actuating said valve means, a quantity of liquid in said bellows andchamber, mechanical means for compressing said bellows and moving saidplug with respect to said valve head and forcing said liquid upwardlyinto said chamber whereby the upward movement of said plug closes saidinlet and opens said outlet so that the gas contained within saidchamber is forced through said outlet by the upward movement of saidliquid.

3. A gas transfer pump comprising a bellows, a plug sealed to one end ofsaid bellows, a valve head sealed to the other end of said bellows, saidvalve head containing a gas inlet, .a gas outlet and a known volumechamber, said inlet, outlet and known volume chamber communicating withsaid other end of said bellows, a valve in said gas inlet, a valve insaid gas outlet, means connecting said inlet and outlet valves to saidplug, a quantity of liquid in said bellows and known volume chamber, apivot pin attached to said plug, a rotatable crankshaft, a connectingrod having one end connected to the eccentric portion of said crankshaftand the other end rotatably connected to said pivot pin, wherebyrotation of said crankshaft will move said bellows relative to saidvalve head causing actuation of said valves and forcing said liquid intosaid chamber so that said gas will be forced through said outlet valve.

References Cited in the file of this patent UNITED STATES PATENTS609,088 Dutton Aug. 16, 1898 1,436,443 Holmes Nov. 21, 1922

